1. Field of the Invention
The present invention relates to a photoelectric converter, and in particular, to a two-dimensional photoelectric converter that is used for facsimile machines, digital copy machines, and X-ray machines.
2. Related Background Art
Conventionally, a scanning system that employs a reducing optical system and a CCD sensor is used for a scanning apparatus, such as a facsimile machine or a digital copy machine. Recently, however, as a consequence of the development of photoelectric conversion semiconductor material, such as amorphous silicon (hereinafter referred to as a-Si), a so-called close-contact sensor has been developed for which a photoelectric conversion device and a signal processor are formed on a large substrate, and by which data are scanned by using an optical system that has the same magnification rate as that of a data source. Furthermore, since a-Si can be employed not only as a photoelectric conversion material but also as a thin film field-effect transistor film (hereinafter referred to as a TFT), both a photoelectric conversion semiconductor layer and a TFT semiconductor layer can be formed at the same time.
The basic structure of a photoelectric converter that uses a-Si is described in the specification for U.S. Pat. No. 4,376,888, or in Japanese Patent Publication No. 62-23944, or Japanese Patent Publication No. 63-6617.
A specific example for the integral forming of an a-Si photosensor and an a-Si TFT is described in the specifications for U.S. Pat. No. 4,931,661, U.S. Pat. No. 5,338,690 and U.S. Pat. No. 5,306,648.
Based on the techniques disclosed in these specifications, the present inventors produced as a sample photoelectric converter a two-dimensional area type in which the number of pixels was drastically increased. The outline of the photoelectric converter will now be described while referring to FIGS. 1 and 2. This device is disclosed in European Patent Publication No. 0660421.
FIGS. 1 and 2 are plan views of a photoelectric converter that has 2000xc3x972000 pixels. To provide 2000xc3x972000 sensors, the number of photoelectric conversion devices that are included in an arrangement are increased in both the vertical and the horizontal directions. For this converter, 2000 control lines (scan lines) are also required, as is indicated by g1 through g2000, and accordingly, 2000 signal lines (data lines) are required, as is indicated by sig1 through sig2000. In addition, the sizes of a scanning circuit and an integrated circuit used for detection (a detection IC) are increased because they have to control and handle 2000 signal lines. When these processes are performed by single, one-chip ICs, the sizes of the chips must be increased, and the yielding manufacturing ratio and the prices are adversely affected. As is shown in FIGS. 1 and 2, in a scan circuit, therefore, sufficient shift registers to handle 100 stages, for example, are formed on a single chip and 20 of these scan circuit chips (SR1-1 through SR1-20) are used. For the detection process for the integrated circuit, 100 processing circuits are formed on a single chip, and 20 of these integrated circuit detection chips (IC-1 through IC-20) are used.
In FIG. 1, 20 chips (SR1-1 through SR1-20) are mounted along the left side (L) and another 20 chips (IC-1 through IC-20) are mounted across the down side (D). Connected to each chip by wire bonding are 100 control lines or signal lines. The portion that is enclosed by broken lines in FIG. 1 corresponds to a photoelectric conversion device array that is arranged as a two-dimensional area. The connection of the detection integrated circuit to an external device is not shown.
In another example, shown in FIG. 2, 10 chips (SR1-1 through SR1-10) are mounted along the left side (L) and 10 chips (SR1-11 through SR1-20) are mounted along the right side (R); and 10 chips (IC-1 through IC-10) are mounted across the upper side (U) and 10 chips (IC-11 through IC-20) are mounted across the down side (D). Since in this structure 1000 lines are provided at each of the upper, down, left and right sides (U, D, L and R), the density of the lines arranged along each side is reduced and the concentration of the wire bonding required on each side is also decreased, thus providing an increased manufacturing yielding ratio. Lines g1, g3, g5, . . . , and g1999 are arranged along the left side (L), while g2, g4, g6, . . . , and g2000 are arranged along the right side (R). That is, the odd numbered control lines are distributed along the left side (L), and the even numbered control lines are distributed along the right side (R). With this arrangement, since each line is pulled out so that the lines are located at equal intervals, the lines are not overly concentrated and the yielding ratio is increased. The wiring across the upper side (U) and the down side (D) is performed in the same manner.
Though not shown, in an additional example, lines g1 through g100, g201 through g300, . . . , and g1801 through g1900 are provided on the left side (L), while lines g101 through g200, g301 through g400, . . . , and g1901 through g2000 are provided on the right side (R). In other words, it is possible for continuous control lines to be distributed to each chip and for these chips to be alternately sorted to the left side and to be right side (to L and to R). With this arrangement, the control lines for a single chip can be controlled sequentially, the adjustment and the setup of drive timing can be facilitated, a circuit does not become complicated, and an inexpensive IC can be used. The same arrangement can be applied for upper and the down sides (U and D), and an inexpensive IC that can perform a continuous process can be used.
During the manufacturing process for a photoelectric converter having large dimensions, however, it is difficult to completely remove minute dust particles; it is especially difficult to remove a contaminant that is peeled off the wall of a thin film deposition device before a semiconductor layer, such as an amorphous layer, is deposited on a substrate, and it is also difficult to remove dust that remains on a substrate before a metal layer is deposited on the substrate. Therefore, it is difficult to eliminate wiring defects, i.e., short circuits or open circuits in lines.
When the short circuits or open circuits in the control lines or the signal lines occur in a photoelectric converter having large dimensions, all of the output signals of the photoelectric converter devices that are connected to the short-circuited are rendered inexact, and the converter can not function as a photoelectric converter.
In other words, as the size of one substrate is increased for the fabrication of a photoelectric converter having large dimensions, losses due to defects that occur during the manufacture of a substrate are also increased.
Further, if the selection of control lines (scanning) is so designed that it is performed in the order corresponding to the direction indicated by arrow AL1 in FIG. 2, the order in which the output terminals for each of the scan circuits SR1-1 through SR1-10 are arranged on the left side (L) in FIG. 2 is the opposite of the order in which the output terminals for each of the scan circuits SR1-11 through SR1-20 are arranged on the right side (R). When the scan circuits that are arranged on both sides are formed by using IC chips having the same structure, connection lines (lines for connecting control lines to the output terminals of the scan circuits) on either the right side (R) or the left side (L) must be formed of multi-layer lines, etc. As a result, the structure of the connection lines becomes complicated and expensive, and the high-density mounting of scan circuits is prevented.
Two types of ICs are prepared for which the orders in which output terminals are located differ, and ICs of one type are arranged on the left side (L), while ICs of the other type are arranged on the right side (R). However, the manufacture of two types of ICs, even though their basic operations are the same, results in higher manufacturing costs.
The above described shortcomings not only apply to scan circuits, but also apply to detection ICs (IC-1 through IC-20) for the output of read signals in a time series.
It is, therefore, a first object of the present invention to reduce a manufacturing costs for a photoelectric converter having large dimensions by providing an increased yielding ratio for each substrate during fabrication of photoelectric converter having large dimensions, and by reducing losses due to defects in each substrate.
It is a second object of the present invention to provide better throughput to accompany an improved efficiency for an inspection procedure during fabrication of photoelectric converters having large dimensions, and to reduce total manufacturing costs that accompany a reduction in the number of components.
It is a third object of the present invention to provide an enhanced function for a photoelectric converter having large dimensions by scanning all of the photoelectric conversion devices in the same direction, and by simplifying signal processing.
It is a fourth object of the present invention to provide a photoelectric converter wherein one type of IC can be easily mounted on all sides, upper, down, right and left (U, D, R and L), of a photoelectric conversion device array.
To achieve the above objects, according to a first aspect of the present invention, a photoelectric converter comprises:
a plurality of substrates, which are located adjacent to each other and on which a plurality of photoelectric conversion devices are two-dimensionally arranged;
either scan circuits or detection circuits, at least, that are arranged on two opposing sides of the photoelectric converter, whereby scanning directions either from the scan circuits or from the detection circuits, which are arranged on the two opposing sides, are capable of being set so as to be performed in like directions.
Furthermore, to achieve the above objects according to a second aspect of the present invention, provided is a photoelectric converter wherein four substrates on which a plurality of photoelectric conversion devices are arranged two-dimensionally are so bonded together two-dimensionally, with two each in a vertical direction and in a horizontal direction, that the photoelectric conversion devices are located adjacent to each other on a plane; wherein, from among the four substrates that are bonded together, two substrates that are not adjacent to each other have such a positional relationship that substrates having the same structure are rotated 180xc2x0 relative to each other on a plane; and wherein the substrates are scanned in the same direction.
According to a third aspect of the present invention, provided is a photoelectric converter wherein a plurality of substrates, on which photoelectric conversion devices are two-dimensionally mounted, are so located and bonded together that the photoelectric conversion devices are located adjacent to each other on a plane; and wherein the plurality of substrates are bonded together at the same locations as those when semiconductor layers are deposited that serve as the photoelectric conversion devices for each of the substrates.
Since a yielding ratio for each substrate during the fabrication process can be increased and losses due to defects on the substrates are reduced, the cost of manufacturing a photoelectric converter having large dimensions can be reduced.
Further, as it is possible to improve the efficiency of an inspection procedure and the throughput that accompanies it, and to reduce the number of required components, and as a result, the cost of manufacturing a photoelectric converter having large dimensions can be reduced.
In addition, since all of the photoelectric conversion devices can be scanned in the same direction and signal processing can be performed at a high speed by a simple device, the cost of manufacturing the photoelectric converter can be reduced, while the function of the photoelectric converter can be improved.
Furthermore, a photoelectric converter wherein the amount of incident light can be detected, as the photoelectric conversion device has only one introduction prevention layer, can be provided at a low price; the optimizing of the process is easy and the yielding ratio can be increased; the manufacturing cost can be reduced; and the SN ratio is high.
The exposure apparatus that employs the above converter differs from conventional X-ray film in that it can project its output very quickly, and in that image processing and data storage are also possible. It has better sensitivity than the film, and a clear image can be obtained with a weak X-ray that will have little adverse effect on a human body.
When the substrates are bonded in consonance with the locations of the substrates when the film is deposited, the characteristics of the photoelectric conversion devices on different substrates that are at the least located at positions adjacent to each other on different substrates can be sequentially equalized.